This volume is the first in-depth study of a recently discovered Sanskrit dharani spell text from around the 5th century CE surviving in two palm-leaf and three paper manuscript compendia from Nepal. This rare Buddhist scripture focuses on the ritual practice of thaumaturgic weather control for successful agriculture through overpowering mythical Nagas. Traditionally, these serpentine beings are held responsible for the amount of rainfall. The six chapters of the Vajratundasamayakalparaja present the vidyadhara spell-master as a ritualist who uses mandalas, mudras and other techniques to gain mastery over the Nagas and thus control the rains. By subjugating the Nagas, favourable weather and good crops are guaranteed. This links this incantation tradition to economic power and the securing of worldly support for the Buddhist community.